A vehicle, such as an autonomous or semi-autonomous vehicle, typically includes sensors. Some sensors provide data about operation of the vehicle, for example, wheel speed, wheel orientation, and engine and transmission data (e.g., temperature, fuel consumption, etc.). Some sensors detect the position or orientation of the vehicle. For example, the sensors may include global positioning system (GPS) sensors; accelerometers such as piezo-electric or microelectromechanical systems (MEMS); gyroscopes such as rate, ring laser, or fiber-optic gyroscopes; inertial measurements units (IMU); and magnetometers. Some sensors detect the external world. For example, the sensors may include radar sensors, scanning laser range finders, light detection and ranging (LIDAR) devices, and image processing sensors such as cameras. The sensors may include communications devices, for example, vehicle-to-infrastructure (V2I) or vehicle-to-vehicle (V2V) devices.
The sensors on the vehicle that detect the external environment are exposed to that external environment. The sensors may be obstructed by dirt, dust, debris, precipitation, insects, etc. Obstructions can degrade the performance of the sensors.